User equipment (UE) and methods for dynamic millimeter wave pencil cell communication

ABSTRACT

Embodiments of a User Equipment (UE), an Evolved Node-B (eNB), small-cell access point (AP), and methods for dynamic millimeter wave pencil cell communication are generally described herein. The UE may receive access point reference signals (APRS) from one or more small-cell access points (AP), and may transmit APRS signal quality measurements to a macro-cell Evolved Node-B (eNB). The UE may receive, from the macro-cell eNB, a message that indicates candidate pencil cells for which the UE is to determine signal quality measurements, the candidate pencil cells supported by the small-cell APs. The UE may receive beam reference signals (BRS) for the candidate pencil cells and may refrain from reception of BRS for pencil cells not included in the message. In some cases, beam-widths of the APRSs may be larger than beam-widths of the BRSs.

PRIORITY CLAIM

This application claims is a U.S. National Stage Filing under 35 U.S.C.371 from International Application No. PCT/US2015/061486, filed Nov. 19,2015 and published in English as WO 2017/019116 on Feb. 2, 2017, whichpriority to U.S. Provisional Patent Application Ser. No. 62/198,247,filed Jul. 29, 2015, each of which is incorporated herein by referencein its entirety.

TECHNICAL FIELD

Embodiments pertain to wireless communications. Some embodiments relateto wireless networks including 3GPP (Third Generation PartnershipProject) networks, 3GPP LTE (Long Term Evolution) networks, and 3GPPLTE-A (LTE Advanced) networks, although the scope of the embodiments isnot limited in this respect. Some embodiments related to WirelessGigabit Alliance (WiGIG) networks. Some embodiments relate to FifthGeneration (5G) networks. Some embodiments relate to communication usingpencil cells, small cells and/or macro cells. Some embodiments relate tomillimeter wave (mmW) communication.

BACKGROUND

A mobile network may support communication with mobile devices. In somecases, small cells may be deployed within a macro cell to providelocalized communication to the mobile devices. For instance, when alarge number of people are gathered at a particular location and/orevent, demand for data communication and/or other communication mayincrease. The usage of small cells may alleviate the increased demand tosome extent, although the mobile network may still become overloaded insome cases. Accordingly, there is a general need for methods and systemsfor enabling communication between the mobile devices and the network inthese and other scenarios.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional diagram of a 3GPP network in accordance with someembodiments;

FIG. 2 is a block diagram of a User Equipment (UE) in accordance withsome embodiments;

FIG. 3 is a block diagram of an Evolved Node-B (eNB) in accordance withsome embodiments;

FIG. 4 is a block diagram of a small-cell access point (AP) inaccordance with some embodiments;

FIG. 5 illustrates an example of a scenario in which a UE may be incommunication with a macro-cell eNB and with multiple small-cell APs inaccordance with some embodiments;

FIG. 6 illustrates the operation of a method of communication inaccordance with some embodiments;

FIG. 7 illustrates another example of a method of communication inaccordance with some embodiments;

FIG. 8 illustrates an example of communication between a UE and amacro-cell eNB in accordance with some embodiments;

FIG. 9 illustrates another example of a method of communication inaccordance with some embodiments;

FIG. 10 illustrates example reference signals in accordance with someembodiments; and

FIG. 11 illustrates an example of transmission of reference signalsaccording to various periodicity parameters in accordance with someembodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 is a functional diagram of a 3GPP network in accordance with someembodiments. The network comprises a radio access network (RAN) (e.g.,as depicted, the E-UTRAN or evolved universal terrestrial radio accessnetwork) 100 and the core network 120 (e.g., shown as an evolved packetcore (EPC)) coupled together through an S1 interface 115. Forconvenience and brevity sake, only a portion of the core network 120, aswell as the RAN 100, is shown.

The core network 120 includes a mobility management entity (MME) 122, aserving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. The RAN 100 includes Evolved Node-B′s (eNBs) 104 (which mayoperate as base stations) for communicating with User Equipment (UE)102. The eNBs 104 may include macro eNBs and low power (LP) eNBs.

The MME 122 is similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 manages mobility aspectsin access such as gateway selection and tracking area list management.The serving GW 124 terminates the interface toward the RAN 100, androutes data packets between the RAN 100 and the core network 120. Inaddition, it may be a local mobility anchor point for inter-eNBhandovers and also may provide an anchor for inter-3GPP mobility. Otherresponsibilities may include lawful intercept, charging, and some policyenforcement. The serving GW 124 and the MME 122 may be implemented inone physical node or separate physical nodes. The PDN GW 126 terminatesan SGi interface toward the packet data network (PDN). The PDN GW 126routes data packets between the EPC 120 and the external PDN, and may bea key node for policy enforcement and charging data collection. It mayalso provide an anchor point for mobility with non-LTE accesses. Theexternal PDN can be any kind of IP network, as well as an IP MultimediaSubsystem (IMS) domain. The PDN GW 126 and the serving GW 124 may beimplemented in one physical node or separated physical nodes.

The eNBs 104 (macro and micro) terminate the air interface protocol andmay be the first point of contact for a UE 102. In some embodiments, aneNB 104 may fulfill various logical functions for the RAN 100 includingbut not limited to RNC (radio network controller functions) such asradio bearer management, uplink and downlink dynamic radio resourcemanagement and data packet scheduling, and mobility management. Inaccordance with embodiments, UEs 102 may be configured to communicateOrthogonal Frequency Division Multiplexing (OFDM) communication signalswith an eNB 104 over a multicarrier communication channel in accordancewith an Orthogonal Frequency Division Multiple Access (OFDMA)communication technique. The OFDM signals may comprise a plurality oforthogonal subcarriers.

The S1 interface 115 is the interface that separates the RAN 100 and theEPC 120. It is split into two parts: the S1-U, which carries trafficdata between the eNBs 104 and the serving GW 124, and the S1-MME, whichis a signaling interface between the eNBs 104 and the MME 122. The X2interface is the interface between eNBs 104. The X2 interface comprisestwo parts, the X2-C and X2-U. The X2-C is the control plane interfacebetween the eNBs 104, while the X2-U is the user plane interface betweenthe eNBs 104.

In some embodiments, the eNB 104, the MME 122 and/or other component inthe network may be communicatively coupled to one or more small-cellaccess points (AP) 106. The small-cell AP 106 may communicate with theUE 102 using techniques such as those described herein, althoughembodiments are not limited as such. As an example, the eNB 104, the MME122 and/or other component may provide the small-cell AP 106 withvarious configuration information related to communication between theUE 102 and the small-cell AP 106. For instance, the communicationbetween the small-cell AP 106 and the UE 102 may include exchanging ofdata using pencil-cell techniques in which a signal from the small-cellAP 106 may be transmitted in a directional manner and may be transmittedwith a relatively high gain. The UE 102 may also receive variousreference signals from the small-cell AP 106. The UE 102 and eNB 104 mayexchange various control messages that may be related to measurementsfor such reception, in some cases. These embodiments will be describedin more detail below.

It should be pointed out that embodiments are not limited to the usageof the example 3GPP network shown in FIG. 1, as other macro-cellnetworks may be used in some cases. Accordingly, the small-cell AP 106(or other small-cell base station component) may be arranged to performsome or all of the techniques and operations described herein as part ofembodiments that may include any suitable macro-cell network.

With cellular networks, LP cells are typically used to extend coverageto indoor areas where outdoor signals do not reach well, or to addnetwork capacity in areas with very dense phone usage, such as trainstations. As used herein, the term low power (LP) eNB refers to anysuitable relatively low power eNB for implementing a narrower cell(narrower than a macro cell) such as a femtocell, a picocell, or a microcell. Femtocell eNBs are typically provided by a mobile network operatorto its residential or enterprise customers. A femtocell is typically thesize of a residential gateway or smaller and generally connects to theuser's broadband line. Once plugged in, the femtocell connects to themobile operator's mobile network and provides extra coverage in a rangeof typically 30 to 50 meters for residential femtocells. Thus, a LP eNBmight be a femtocell eNB since it is coupled through the PDN GW 126.Similarly, a picocell is a wireless communication system typicallycovering a small area, such as in-building (offices, shopping malls,train stations, etc.), or more recently in-aircraft. A picocell eNB cangenerally connect through the X2 link to another eNB such as a macro eNBthrough its base station controller (BSC) functionality. Thus, LP eNBmay be implemented with a picocell eNB since it is coupled to a macroeNB via an X2 interface. Picocell eNBs or other LP eNBs may incorporatesome or all functionality of a macro eNB. In some cases, this may bereferred to as an access point base station or enterprise femtocell.

In some embodiments, a downlink resource grid may be used for downlinktransmissions from an eNB 104 to a UE 102, while uplink transmissionfrom the UE 102 to the eNB 104 may utilize similar techniques. The gridmay be a time-frequency grid, called a resource grid or time-frequencyresource grid, which is the physical resource in the downlink in eachslot. Such a time-frequency plane representation is a common practicefor OFDM systems, which makes it intuitive for radio resourceallocation. Each column and each row of the resource grid correspond toone OFDM symbol and one OFDM subcarrier, respectively. The duration ofthe resource grid in the time domain corresponds to one slot in a radioframe. The smallest time-frequency unit in a resource grid is denoted asa resource element (RE). Each resource grid comprises a number ofresource blocks (RBs), which describe the mapping of certain physicalchannels to resource elements. Each resource block comprises acollection of resource elements in the frequency domain and mayrepresent the smallest quanta of resources that currently can beallocated. There are several different physical downlink channels thatare conveyed using such resource blocks. With particular relevance tothis disclosure, two of these physical downlink channels are thephysical downlink shared channel and the physical down link controlchannel.

The physical downlink shared channel (PDSCH) carries user data andhigher-layer signaling to a UE 102 (FIG. 1). The physical downlinkcontrol channel (PDCCH) carries information about the transport formatand resource allocations related to the PDSCH channel, among otherthings. It also informs the UE 102 about the transport format, resourceallocation, and hybrid automatic repeat request (HARQ) informationrelated to the uplink shared channel. Typically, downlink scheduling(e.g., assigning control and shared channel resource blocks to UEs 102within a cell) may be performed at the eNB 104 based on channel qualityinformation fed back from the UEs 102 to the eNB 104, and then thedownlink resource assignment information may be sent to a UE 102 on thecontrol channel (PDCCH) used for (assigned to) the UE 102.

The PDCCH uses CCEs (control channel elements) to convey the controlinformation. Before being mapped to resource elements, the PDCCHcomplex-valued symbols are first organized into quadruplets, which arethen permuted using a sub-block inter-leaver for rate matching. EachPDCCH is transmitted using one or more of these control channel elements(CCEs), where each CCE corresponds to nine sets of four physicalresource elements known as resource element groups (REGs). Four QPSKsymbols are mapped to each REG. The PDCCH can be transmitted using oneor more CCEs, depending on the size of DCI and the channel condition.There may be four or more different PDCCH formats defined in LTE withdifferent numbers of CCEs (e.g., aggregation level, L=1, 2, 4, or 8).

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group), and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablehardware components that provide the described functionality. In someembodiments, the circuitry may be implemented in, or functionsassociated with the circuitry may be implemented by, one or moresoftware or firmware modules. In some embodiments, circuitry may includelogic, at least partially operable in hardware. Embodiments describedherein may be implemented into a system using any suitably configuredhardware and/or software.

FIG. 2 is a block diagram of a User Equipment (UE) in accordance withsome embodiments. The UE 200 may be suitable for use as a UE 102 asdepicted in FIG. 1. In some embodiments, the UE 200 may includeapplication circuitry 202, baseband circuitry 204, Radio Frequency (RF)circuitry 206, front-end module (FEM) circuitry 208 and one or moreantennas 210, coupled together at least as shown. In some embodiments,other circuitry or arrangements may include one or more elements and/orcomponents of the application circuitry 202, the baseband circuitry 204,the RF circuitry 206 and/or the FEM circuitry 208, and may also includeother elements and/or components in some cases. As an example,“processing circuitry” may include one or more elements and/orcomponents, some or all of which may be included in the applicationcircuitry 202 and/or the baseband circuitry 204. As another example,“transceiver circuitry” may include one or more elements and/orcomponents, some or all of which may be included in the RF circuitry 206and/or the FEM circuitry 208. These examples are not limiting, however,as the processing circuitry and/or the transceiver circuitry may alsoinclude other elements and/or components in some cases.

The application circuitry 202 may include one or more applicationprocessors. For example, the application circuitry 202 may includecircuitry such as, but not limited to, one or more single-core ormulti-core processors. The processor(s) may include any combination ofgeneral-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the system.

The baseband circuitry 204 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 204 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 206 and to generate baseband signals fora transmit signal path of the RF circuitry 206. Baseband processingcircuitry 204 may interface with the application circuitry 202 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 206. For example, in some embodiments,the baseband circuitry 204 may include a second generation (2G) basebandprocessor 204 a, third generation (3G) baseband processor 204 b, fourthgeneration (4G) baseband processor 204 c, and/or other basebandprocessor(s) 204 d for other existing generations, generations indevelopment or to be developed in the future (e.g., fifth generation(5G), 6G, etc.). The baseband circuitry 204 (e.g., one or more ofbaseband processors 204 a-d) may handle various radio control functionsthat enable communication with one or more radio networks via the RFcircuitry 206. The radio control functions may include, but are notlimited to, signal modulation/demodulation, encoding/decoding, radiofrequency shifting, etc. In some embodiments, modulation/demodulationcircuitry of the baseband circuitry 204 may include Fast-FourierTransform (FFT), precoding, and/or constellation mapping/demappingfunctionality. In some embodiments, encoding/decoding circuitry of thebaseband circuitry 204 may include convolution, tail-biting convolution,turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoderfunctionality. Embodiments of modulation/demodulation andencoder/decoder functionality are not limited to these examples and mayinclude other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry 204 may include elements ofa protocol stack such as, for example, elements of an evolved universalterrestrial radio access network (EUTRAN) protocol including, forexample, physical (PHY), media access control (MAC), radio link control(RLC), packet data convergence protocol (PDCP), and/or radio resourcecontrol (RRC) elements. A central processing unit (CPU) 204 e of thebaseband circuitry 204 may be configured to run elements of the protocolstack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. Insome embodiments, the baseband circuitry may include one or more audiodigital signal processor(s) (DSP) 204 f. The audio DSP(s) 204 f may beinclude elements for compression/decompression and echo cancellation andmay include other suitable processing elements in other embodiments.Components of the baseband circuitry may be suitably combined in asingle chip, a single chipset, or disposed on a same circuit board insome embodiments. In some embodiments, some or all of the constituentcomponents of the baseband circuitry 204 and the application circuitry202 may be implemented together such as, for example, on a system on achip (SOC).

In some embodiments, the baseband circuitry 204 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 204 may supportcommunication with an evolved universal terrestrial radio access network(EUTRAN) and/or other wireless metropolitan area networks (WMAN), awireless local area network (WLAN), a wireless personal area network(WPAN). Embodiments in which the baseband circuitry 204 is configured tosupport radio communications of more than one wireless protocol may bereferred to as multi-mode baseband circuitry.

RF circuitry 206 may enable communication with wireless networks usingmodulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 206 may include switches, filters,amplifiers, etc. to facilitate the communication with the wirelessnetwork. RF circuitry 206 may include a receive signal path which mayinclude circuitry to down-convert RF signals received from the FEMcircuitry 208 and provide baseband signals to the baseband circuitry204. RF circuitry 206 may also include a transmit signal path which mayinclude circuitry to up-convert baseband signals provided by thebaseband circuitry 204 and provide RF output signals to the FEMcircuitry 208 for transmission.

In some embodiments, the RF circuitry 206 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 206 may include mixer circuitry 206 a, amplifier circuitry 206b and filter circuitry 206 c. The transmit signal path of the RFcircuitry 206 may include filter circuitry 206 c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206 d forsynthesizing a frequency for use by the mixer circuitry 206 a of thereceive signal path and the transmit signal path. In some embodiments,the mixer circuitry 206 a of the receive signal path may be configuredto down-convert RF signals received from the FEM circuitry 208 based onthe synthesized frequency provided by synthesizer circuitry 206 d. Theamplifier circuitry 206 b may be configured to amplify thedown-converted signals and the filter circuitry 206 c may be a low-passfilter (LPF) or band-pass filter (BPF) configured to remove unwantedsignals from the down-converted signals to generate output basebandsignals. Output baseband signals may be provided to the basebandcircuitry 204 for further processing. In some embodiments, the outputbaseband signals may be zero-frequency baseband signals, although thisis not a requirement. In some embodiments, mixer circuitry 206 a of thereceive signal path may comprise passive mixers, although the scope ofthe embodiments is not limited in this respect. In some embodiments, themixer circuitry 206 a of the transmit signal path may be configured toup-convert input baseband signals based on the synthesized frequencyprovided by the synthesizer circuitry 206 d to generate RF outputsignals for the FEM circuitry 208. The baseband signals may be providedby the baseband circuitry 204 and may be filtered by filter circuitry206 c. The filter circuitry 206 c may include a low-pass filter (LPF),although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the receive signalpath and the mixer circuitry 206 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedownconversion and/or upconversion respectively. In some embodiments,the mixer circuitry 206 a of the receive signal path and the mixercircuitry 206 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 206 a of thereceive signal path and the mixer circuitry 206 a may be arranged fordirect downconversion and/or direct upconversion, respectively. In someembodiments, the mixer circuitry 206 a of the receive signal path andthe mixer circuitry 206 a of the transmit signal path may be configuredfor super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 206 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry204 may include a digital baseband interface to communicate with the RFcircuitry 206. In some dual-mode embodiments, a separate radio ICcircuitry may be provided for processing signals for each spectrum,although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 206 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 206 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider. The synthesizer circuitry 206 d may be configured tosynthesize an output frequency for use by the mixer circuitry 206 a ofthe RF circuitry 206 based on a frequency input and a divider controlinput. In some embodiments, the synthesizer circuitry 206 d may be afractional N/N+1 synthesizer. In some embodiments, frequency input maybe provided by a voltage controlled oscillator (VCO), although that isnot a requirement. Divider control input may be provided by either thebaseband circuitry 204 or the applications processor 202 depending onthe desired output frequency. In some embodiments, a divider controlinput (e.g., N) may be determined from a look-up table based on achannel indicated by the applications processor 202.

Synthesizer circuitry 206 d of the RF circuitry 206 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 206 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (f_(LO)). Insome embodiments, the RF circuitry 206 may include an IQ/polarconverter.

FEM circuitry 208 may include a receive signal path which may includecircuitry configured to operate on RF signals received from one or moreantennas 210, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 206 for furtherprocessing. FEM circuitry 208 may also include a transmit signal pathwhich may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 206 for transmission by one ormore of the one or more antennas 210.

In some embodiments, the FEM circuitry 208 may include a TX/RX switch toswitch between transmit mode and receive mode operation. The FEMcircuitry may include a receive signal path and a transmit signal path.The receive signal path of the FEM circuitry may include a low-noiseamplifier (LNA) to amplify received RF signals and provide the amplifiedreceived RF signals as an output (e.g., to the RF circuitry 206). Thetransmit signal path of the FEM circuitry 208 may include a poweramplifier (PA) to amplify input RF signals (e.g., provided by RFcircuitry 206), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 210. In some embodiments, the UE 200 may include additionalelements such as, for example, memory/storage, display, camera, sensor,and/or input/output (I/O) interface.

FIG. 3 is a block diagram of an Evolved Node-B (eNB) in accordance withsome embodiments. It should be noted that in some embodiments, the eNB300 may be a stationary non-mobile device. The eNB 300 may be suitablefor use as an eNB 104 as depicted in FIG. 1. The eNB 300 may includephysical layer circuitry 302 and a transceiver 305, one or both of whichmay enable transmission and reception of signals to and from the UE 200,other eNBs, other UEs or other devices using one or more antennas 301.As an example, the physical layer circuitry 302 may perform variousencoding and decoding functions that may include formation of basebandsignals for transmission and decoding of received signals. As anotherexample, the transceiver 305 may perform various transmission andreception functions such as conversion of signals between a basebandrange and a Radio Frequency (RF) range. Accordingly, the physical layercircuitry 302 and the transceiver 305 may be separate components or maybe part of a combined component. In addition, some of the describedfunctionality related to transmission and reception of signals may beperformed by a combination that may include one, any or all of thephysical layer circuitry 302, the transceiver 305, and other componentsor layers. The eNB 300 may also include medium access control layer(MAC) circuitry 304 for controlling access to the wireless medium. TheeNB 300 may also include processing circuitry 306 and memory 308arranged to perform the operations described herein. The eNB 300 mayalso include one or more interfaces 310, which may enable communicationwith other components, including other eNBs 104 (FIG. 1), the small-cellAP 106, components in the EPC 120 (FIG. 1) or other network components.In addition, the interfaces 310 may enable communication with othercomponents that may not be shown in FIG. 1, including componentsexternal to the network. The interfaces 310 may be wired or wireless ora combination thereof.

FIG. 4 is a block diagram of a small-cell access point (AP) inaccordance with some embodiments. The small-cell AP 400 may includephysical layer circuitry 402 and a transceiver 405, one or both of whichmay enable transmission and reception of signals to and from the UE 200,eNB 300, other eNBs, other UEs or other devices using one or moreantennas 401. As an example, the physical layer circuitry 402 mayperform various encoding and decoding functions that may includeformation of baseband signals for transmission and decoding of receivedsignals. As another example, the transceiver 405 may perform varioustransmission and reception functions such as conversion of signalsbetween a baseband range and a Radio Frequency (RF) range. Accordingly,the physical layer circuitry 402 and the transceiver 405 may be separatecomponents or may be part of a combined component. In addition, some ofthe described functionality related to transmission and reception ofsignals may be performed by a combination that may include one, any orall of the physical layer circuitry 402, the transceiver 405, and othercomponents or layers. The small-cell AP 400 may also include mediumaccess control layer (MAC) circuitry 404 for controlling access to thewireless medium. The small-cell AP 400 may also include processingcircuitry 406 and memory 408 arranged to perform the operationsdescribed herein. The small-cell AP 400 may also include one or moreinterfaces 410, which may enable communication with other components,including the eNB 104 (FIG. 1), components in the EPC 120 (FIG. 1) orother network components. In addition, the interfaces 410 may enablecommunication with other components that may not be shown in FIG. 1,including components external to the network. The interfaces 410 may bewired or wireless or a combination thereof.

The antennas 210, 301, 401 may comprise one or more directional oromnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas orother types of antennas suitable for transmission of RF signals. In somemultiple-input multiple-output (MIMO) embodiments, the antennas 210,301, 401 may be effectively separated to take advantage of spatialdiversity and the different channel characteristics that may result.

In some embodiments, the UE 200 and/or the eNB 300 and/or the small-cellAP 400 may be a mobile device and may be a portable wirelesscommunication device, such as a personal digital assistant (PDA), alaptop or portable computer with wireless communication capability, aweb tablet, a wireless telephone, a smartphone, a wireless headset, apager, an instant messaging device, a digital camera, an access point, atelevision, a wearable device such as a medical device (e.g., a heartrate monitor, a blood pressure monitor, etc.), or other device that mayreceive and/or transmit information wirelessly. In some embodiments, theUE 200 and/or eNB 300 and/or small-cell AP 400 may be configured tooperate in accordance with 3GPP standards, although the scope of theembodiments is not limited in this respect. In some embodiments, the UE200 and/or eNB 300 and/or small-cell AP 400 may be configured to operatein accordance with one or more IEEE 802.11 standards and/or wirelesslocal area network (WLAN) standards, although the scope of theembodiments is not limited in this respect. Mobile devices or otherdevices in some embodiments may be configured to operate according toother protocols or standards, including IEEE 802.11 or other IEEEstandards. In some embodiments, the UE 200, eNB 300, small-cell AP 400or other device may include one or more of a keyboard, a display, anon-volatile memory port, multiple antennas, a graphics processor, anapplication processor, speakers, and other mobile device elements. Thedisplay may be an LCD screen including a touch screen.

Although the UE 200, the eNB 300, and the small-cell AP 400 are eachillustrated as having several separate functional elements, one or moreof the functional elements may be combined and may be implemented bycombinations of software-configured elements, such as processingelements including digital signal processors (DSPs), and/or otherhardware elements. For example, some elements may comprise one or moremicroprocessors, DSPs, field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

It should be noted that in some embodiments, an apparatus used by the UE200 and/or eNB 300 and/or small-cell AP 400 may include variouscomponents of the UE 200 and/or the eNB 300 and/or the small-cell AP 400as shown in FIGS. 2-4. Accordingly, techniques and operations describedherein that refer to the UE 200 (or 102) may be applicable to anapparatus for a UE. In addition, techniques and operations describedherein that refer to the eNB 300 (or 104) may be applicable to anapparatus for an eNB. In addition, techniques and operations describedherein that refer to the small-cell AP 400 (or 106) may be applicable toan apparatus for a small-cell AP.

In accordance with some embodiments, the UE 102 may receive access pointreference signals (APRS) from one or more small-cell APs 106, and maytransmit APRS signal quality measurements to a macro-cell eNB 104. TheUE 102 may receive, from the macro-cell eNB 104, a message thatindicates candidate pencil cells for which the UE 102 is to determinesignal quality measurements, the candidate pencil cells supported by thesmall-cell APs 106. The UE 102 may receive, from the small-cell APs 106,beam reference signals (BRS) for the candidate pencil cells and mayrefrain from reception of BRS for pencil cells not included in themessage. In some cases, beam-widths of the APRSs may be larger thanbeam-widths of the BRSs. These embodiments are described in more detailbelow.

FIG. 5 illustrates an example of a scenario in which a UE may be incommunication with a macro-cell eNB and with multiple small-cell APs inaccordance with some embodiments. Although the example scenario 500shown in FIG. 5 may illustrate some or all aspects of techniquesdisclosed herein, it is understood that embodiments are not limited bythis example scenario 500. It should also be noted that embodiments arenot limited to the components shown in the example scenario 500.Embodiments are also not limited to the number of components shown or tothe arrangement of the components as shown in FIG. 5. As an example,embodiments are not limited to usage of the UE 102, as other mobiledevices may be used in some cases. For instance, a station (STA)arranged to communicate using a wireless local area network (WLAN)protocol (or other protocol) may be used. As another example,embodiments are not limited to usage of the eNB 104 (or macro-cell eNB104 as shown), as other base station devices may be used in some cases.As another example, embodiments are not limited to the usage of thesmall-cell APs 106, as other base station components or other componentsmay be used in some cases.

In the example scenario 500, the UE 102 may exchange packets, signalsand/or messages with the eNB 104 using any suitable communicationprotocol, which may or may not be included as part of one or morestandards. As a non-limiting example, the UE 102 may be arranged tocommunicate with the eNB 104 using a Third Generation PartnershipProtocol (3GPP) Long Term Evolution (LTE) protocol in some cases. The UE102 may also exchange packets, signals and/or messages with thesmall-cell APs 106 using any suitable communication protocol, which mayor may not be the same protocol used for communication with the eNB 104.For instance, the UE 102 may be arranged to communicate with thesmall-cell APs 106 using a Fifth Generation (5G) protocol and/or an IEEE802.11 protocol in some cases.

In addition, in the example scenario 500, the small-cell APs 106 maycommunicate with the eNB 104 and/or other network components using anysuitable links and/or interfaces, which may be wireless or wired or acombination thereof. As an example, back-end communication between thesmall-cell APs 106 and the MME 122 and/or eNB 104 may be used. Forinstance, the small-cell APs 106 may be informed of configurationinformation related to communication between the small-cell APs 106 andthe UEs 102.

In the example scenario 500, the eNB 104 may be configured to operate asa macro-cell eNB 104 (or macro eNB 104) in some cases. Accordingly, acoverage area 505 of the eNB 104 may comprise or overlap one or morecoverage areas of small-cell APs 106. As a non-limiting example, thesmall-cell APs 106 may be installed on buildings. As shown in FIG. 5,the UE 102 may physically move along a path that may include points A-D.The first small-cell AP 106 labeled “S1” may support transmissionaccording to multiple pencil cells such as those labeled 510. The secondsmall-cell AP 106 labeled “S2” may support transmission according tomultiple pencil cells such as those labeled 520. In a similar manner,the other small-cell APs 106 labeled S3-S12 may support transmissionaccording to multiple pencil cells as shown.

When the UE 102 is located at point A, the UE 102 may be in coverage ofsmall-cell APs S1 and/or S2. Accordingly, one or more of the pencilcells 510 and/or 520 may be able to provide directional, narrow-beam,high-gain coverage to the UE 102 based on the physical layout of thesmall-cell APs S1 and/or S2, the location of the UE 102 and/or otherfactors such as obstacles in the environment or other factors.Similarly, point B may be in coverage of small-cell APs S3, S4 and/orS5, point C may be in coverage of small-cell APs S7, S8 and/or S9, andpoint D may be in coverage of small-cell APs S10 and/or S11.Accordingly, the optimal set of pencil cells and/or small-cell APs 106for the UE 102 may vary with movement of the UE 102.

It should also be pointed out that coordinated multi-point transmission(CoMP) techniques and/or multi-connectivity techniques may be used insome embodiments. As an example, signals may be transmitted to the UE102 from one or more small-cell APs 106 and/or pencil cells in a mannerwhich enables diversity gain at the UE 102. For instance, the same datapacket may be transmitted from two or more different pencil cells forreception at the UE 102, which may use diversity combining or othertechniques to receive the multiple copies of the data packet.

As a non-limiting example, in scenarios such as 500 and/or others,millimeter wave (mmW) small cells may be deployed in the coverage of amacro cell operating at below 6 GHz. Such operation may be applicablefor a heterogeneous network structure for future 5G mobile systemsand/or other systems. The usage of pencil beams with relatively narrowbeam-widths (such as 5 to 15 degrees, for instance) and relatively highantenna gains and/or beamforming gains may be used by mmW small-cell APs106 to achieve link budget target and energy efficient communication, insome cases. Each pencil beam may be viewed as a pencil cell which can bedetected by a dedicated signature signal sequence for the pencil cell.In an environment with ultra-densely deployed mmW small cells, forinstance, it may be possible or likely that the UE 102 may be reached bymultiple pencil beams experiencing possibly different path losses. Thebeams may originate from one or more mmW small-cell APs 106. In somecases, in order to establish reliable, energy efficient and/or high datarate communication path between a mmW UE 102 and a radio access network(RAN), it may be beneficial to select and allocate a set of optimalpencil beams to serve the UE 102. Due to the mobility of mmW UEs 102 andvariation of surrounding environment, it is possible that the set ofoptimal pencil beams may vary according to the dynamics of thepropagation channels between the UE 102 and small-cell APs 106. As aresult, components of the RAN, such as the macro-cell eNB 104, may tracksuch dynamics so as to provide a consistent high data rate service tothe UE 102.

FIG. 6 illustrates the operation of a method of communication inaccordance with some embodiments. It is important to note thatembodiments of the method 600 may include additional or even feweroperations or processes in comparison to what is illustrated in FIG. 6.In addition, embodiments of the method 600 are not necessarily limitedto the chronological order that is shown in FIG. 6. In describing themethod 600, reference may be made to FIGS. 1-5 and 7-11, although it isunderstood that the method 600 may be practiced with any other suitablesystems, interfaces and components.

In addition, while the method 600 and other methods described herein mayrefer to eNBs 104 or UEs 102 operating in accordance with 3GPP or otherstandards, embodiments of those methods are not limited to just thoseeNBs 104 or UEs 102 and may also be practiced on other devices, such asa Wi-Fi access point (AP) or user station (STA). The method 600 andother methods described herein may also refer to small-cell APs 106 (orother APs 106) that may operate in accordance with one or more IEEE802.11 standards, WiGIG standards, 5G standards or other standards, butembodiments of those methods are not limited to usage of APs 106 and/oroperation according to those standards. For instance, other base stationcomponents may be configured to operate as small-cell base stations insome cases.

In addition, the method 600 and other methods described herein may bepracticed by wireless devices configured to operate in other suitabletypes of wireless communication systems, including systems configured tooperate according to various IEEE standards such as IEEE 802.11. Themethod 600 may also refer to an apparatus for a UE 102 and/or eNB 104and/or small-cell AP 106 and/or other device described above.

At operation 605 of the method 600, a UE 102 may receive, from amacro-cell eNB 104, one or more small-cell AP control messages. In someembodiments, the small-cell AP control messages may indicate one or moresmall-cell APs 106 from which the UE 102 is to receive one or moreaccess point reference signals (APRS). As an example, the small-cell APcontrol messages may include information related to the APRS and/or thesmall-cell APs 106. Such information may include, but is not limited to,signature sequences for the APRSs, identifiers of the small-cell APs 106from which the APRSs are to be received, channel resources to be usedfor the reception, timing in which the APRSs are to be received and/orother suitable information. In some embodiments, the small-cell APcontrol messages may include a “small-cell search request” that mayrequest that the UE 102 determine small-cell signal quality measurementsbased on reception of the APRSs.

In addition, it should be noted that embodiments are not limited to theusage of small-cell AP control messages, as other control messagesand/or other messages may be used for communication of such informationrelated to the APRS and/or the small-cell APs 106. For instance, suchinformation may be included in other messages that may or may not bededicated for communication of the information.

In some embodiments, the eNB 104 may be configured to operate as amacro-cell eNB 104. As an example, a coverage area of the macro-cell eNB104 may be larger than a combined coverage area that comprises coverageareas of the small-cell APs 106. That is, the coverage areas of thesmall-cell APs 106 may be a sub-region of the coverage area of themacro-cell eNB 104. This example is not limiting, however. In somecases, one or more of the small-cell coverage areas (or portions ofthem) may not necessarily be included in the macro-cell coverage area.

At operation 610, the UE 102 may receive one or more APRSs from one ormore small-cell APs 106. In some embodiments, the APRSs may be receivedfrom small-cell APs 106 indicated in the small-cell AP control messagesdescribed previously, although embodiments are not limited as such.

It should be noted that in some embodiments, signals such as thesmall-cell AP control messages and/or others may be received from theeNB 104 in first channel resources that may be different from and/orexclusive to second channel resources in which other signals (such asthe APRSs) are received from the small-cell APs 106. As a non-limitingexample, the first and second channel resources may both be located atcentimeter wave (cmW) frequencies, which may be different in some cases.As another non-limiting example, frequency bands used for communicationwith the eNB 104 and for communication with the small-cell APs 106 maybe non-overlapping in some cases.

As an example, the APRSs may be transmitted by the small-cell APs 106 inan omni-directional manner. As another example, a beam-width of 120, 90or 45 degrees may be used. These examples are not limiting, however, asother suitable beam-widths may be used for the transmission of the APRS.

At operation 615, the UE 102 may transmit, to the eNB 104, one or moreAP signal quality measurements. In some embodiments, the measurementsmay be based on the reception of APRSs at the UE 102. For instance, theUE 102 may receive the APRSs and may perform the measurements, in somecases. The AP signal quality measurements may include any suitablemeasurements such as received signal strength indicator (RSSI),reference signal received power (RSRP), reference signal receivedquality (RSRQ), signal-to-noise ratio (SNR),signal-to-interference-plus-noise ratio (SINR) and/or any suitablemeasurement related to the received APRS. Such measurements may beincluded in one or more standards, in some cases, although embodimentsare not so limited. The AP signal quality measurements may betransmitted in one or more control messages or other messages, which mayor may not be dedicated for such purposes.

In some embodiments, the AP signal quality measurements may enable theeNB 104 to determine which small-cell APs 106 may be in the vicinity ofthe UE 102 and/or which small-cell APs 106 may have a strong wirelesslink with the UE 102.

At operation 620, the UE 102 may receive, from the eNB 104, one or morepencil cell control messages that may indicate one or more candidatepencil cells for which the UE 102 is to determine signal qualitymeasurements. At operation 625, the UE 102 may receive, from thesmall-cell APs 106, beam reference signals (BRS) for the candidatepencil cells. At operation 630, the UE 102 may refrain from reception ofBRSs from the small-cell APs 106 for pencil cells not included in thepencil cell control message. In some cases, the UE 102 may refrain fromreception of BRSs from the small-cell APs 106 for pencil cells excludedfrom the pencil cell control message. In some embodiments, the pencilcell control messages may include a “pencil cell search request” thatmay request that the UE 102 determine pencil cell signal qualitymeasurements based on reception of the BRSs.

It should be noted that the indication of which candidate pencil cellsand/or BRSs that the UE 102 is to receive may enable the UE 102 toperform measurements on a relatively small number (or a manageablenumber) of pencil cells. That is, the indicated candidate pencil cellsmay be a subset of a total number of pencil cells supported by thesmall-cell APs 102. In some cases, the UE 102 may benefit from nothaving to receive BRSs and perform measurements on the total number ofpencil cells.

In some embodiments, the pencil cell control messages may includeinformation related to the BRS and/or the pencil cells and/or thesmall-cell APs 106. Such information may include, but is not limited to,signature sequences for the BRSs, identifiers of the pencil cells and/orsmall-cell APs 106 from which the BRSs are to be received, channelresources to be used for the reception, timing in which the BRSs are tobe received and/or other suitable information. In addition, it should benoted that embodiments are not limited to the usage of pencil cellcontrol messages, as other control messages and/or other messages may beused for communication of such information. For instance, suchinformation may be included in other messages that may or may not bededicated for communication of the information.

As described herein, a small-cell AP 106 may support multiple pencilcells in some cases. In some embodiments, a coverage area of the APRSfor the small-cell AP 106 may be larger than a combined coverage areathat comprises coverage areas of BRSs for multiple pencil cellssupported by the small-cell AP 106. As a non-limiting example, a portionof the coverage area of the APRS (which may be referred to as“small-cell coverage” in some cases) may be divided into smaller cellsthat may be used by the small-cell AP 106 for directional high-gaincommunication with the UE 102 in a relatively small and/or narrow area.That is, one or more coverage areas of the pencil cells may besub-regions of the coverage area of the small-cell AP 106. This exampleis not limiting, however. In some cases, one or more of the pencil cellcoverage areas (or portions of them) may not necessarily be included inthe coverage area of the small-cell AP 106.

Accordingly, a relatively narrow beam-width may be used by thesmall-cell AP 106 for transmission according to a pencil cell. That is,directional transmission using beam-forming techniques and/or othertechniques may be used for transmission according to the pencil cell.For instance, a beam-width used for transmission according to a pencilcell may be more narrow than a beam-width used for transmission of theAPRS. As a non-limiting example, the beam-width for the APRS may be atleast 90 degrees and the beam-width for the pencil cells may be at most15 degrees. As another non-limiting example, the beam-widths for thepencil cells may be included in a range of 5 to 15 degrees. As anothernon-limiting example, the APRS may be transmitted in an omni-directionalmanner.

In addition, a beam-forming gain and/or other gain may be applied to thetransmission according to the pencil cells. As a non-limiting example,the transmission of the BRS by the small-cell AP 106 may be performedusing 10 dB of gain in comparison to the transmission of the APRS.Embodiments are not limited to the gain of 10 dB, however, as 5, 15, 20dB or other suitable value may be used in some cases.

In some embodiments, at least one of the small-cell APs 106 may supportmultiple candidate pencil cells for which assigned BRSs are different.For instance, signature sequences upon which the BRSs are based may bedifferent for different pencil cells. In some cases, such a differencemay enable the UE 102 to identify which pencil cell is being used, bythe small-cell AP 106, for transmission. It should also be noted thatthe pencil cell control message may indicate candidate pencil cells thatmay or may not be supported by the same small-cell AP 106. As anexample, some of the candidate pencil cells may be supported bydifferent small-cell APs 106. For instance, the UE 102 may be located onthe edge of coverage between two small-cell APs 106, and the eNB 104 mayidentify one or more pencil cells from each of the two differentsmall-cell APs 106 that may be candidates for usage by the UE 102.Referring to FIG. 5, when the UE 102 is located at point A, one or morepencil cells 510 supported by the “S1” small-cell AP 106 and one or morepencil cells 520 supported by the “S2” small-cell AP 106 may becandidate pencil cells for the UE 102. As another example, some or allof the candidate pencil cells may be supported by a same small-cell AP106 in some cases.

At operation 635, the UE 102 may transmit, to the eNB 104, pencil cellsignal quality measurements. In some embodiments, the measurements maybe based on the reception of BRSs at the UE 102. For instance, the UE102 may receive the BRSs and may perform the measurements, in somecases. The pencil cell signal quality measurements may include anysuitable measurements such as received signal strength indicator (RSSI),reference signal received power (RSRP), reference signal receivedquality (RSRQ), signal-to-noise ratio (SNR),signal-to-interference-plus-noise ratio (SINR) and/or any suitablemeasurement related to the received APRS. Such measurements may beincluded in one or more standards, in some cases, although embodimentsare not so limited. The pencil cell signal quality measurements may betransmitted in one or more control messages or other messages, which mayor may not be dedicated for such purposes. In some embodiments, thepencil cell signal quality measurements may enable the eNB 104 todetermine which pencil cells may be in the vicinity of the UE 102 and/orwhich small-cell APs 106 may have a strong wireless link with the UE102.

At operation 640, the UE 102 may receive, from the eNB 104, one or morepencil cell configuration messages. In some embodiments, the messagesmay indicate a candidate pencil cell selected, by the eNB 104, forexchanging of data messages with the UE 102. At operation 645, the UE102 may receive, according to the selected candidate pencil cell, a datamessage from a corresponding small-cell AP 106 that supports theselected candidate pencil cell. That is, the UE 102 may begin to receivedata from the corresponding small-cell AP 106 according to the selectedcandidate pencil cell.

In some embodiments, the UE 102 may continue to perform measurements onAPRS and/or BRS in order to monitor signal quality from the pencil cellsand/or small-cell APs 106. As an example, the UE 102 may transmit suchmeasurements (which may be updated measurements, in some cases) in aperiodic manner according to a periodicity parameter. As anotherexample, the UE 102 may transmit the measurements in a non-periodicmanner. For instance, the eNB 104 may request the measurements in somecases. As another example, the eNB 104 may inform the UE 102 of a newgroup of candidate pencil cells for which the UE 102 is to performmeasurements. As another example, the eNB 104 may indicate to the UE 102to hand-off to another pencil cell. In some cases, the pencil cell towhich the UE 102 is to hand-off may be included in the original group ofcandidate pencil cells (such as indicated in operation 620) and/or inthe new group of candidate pencil cells, although embodiments are notlimited as such. As another example, the eNB 104 may indicate areconfiguration, by the UE 102, from the selected candidate pencil cellto a reconfigured candidate pencil cell for exchanging of data messageswith the UE 102. The UE 102 may receive, according to the reconfiguredcandidate pencil cell, a data message from a corresponding small-cell APthat supports the reconfigured candidate pencil cell. It should be notedthat embodiments are not limited to these example operations related tohand-off and/or reconfiguration, as other operations may be used in somecases, in addition to or instead of the operations just described.

In some embodiments, different channel resources may be used fordifferent communication by the UE 102. As a non-limiting example, the UE102 may exchange control messages with the eNB 104 using macro-cellchannel resources located at a first centimeter wave (cmW) frequency.The UE 102 may receive APRSs from the small-cell APs 106 in small-cellchannel resources at a second cmW frequency. The small-cell channelresources may be different from, exclusive to and/or non-overlappingwith the macro-cell channel resources. The UE 102 may receive BRSs fromthe small-cell APs 106 according to the candidate pencil cells in pencilcell channel resources at a millimeter save (mmW) frequency.Accordingly, the pencil cell channel resources may be different from,exclusive to and/or non-overlapping with the macro-cell channelresources and the small-cell channel resources. In some cases, the UE102 may receive data from a small-cell AP 106 according to a selectedcandidate pencil cell using channel resources at an mmW frequency, whichmay or may not be the same mmW frequency used for the reception of theBRSs.

It should be noted that various techniques and/or designs may enabletransmission and/or reception of signals by the UE 102 in multiplefrequency bands, in some cases. As an example, a group of one or moreantennas may be used by the UE 102 to transmit and/or receive signals indifferent frequency bands. It is understood that additional components,such as diplexers or other components, may be included in some sucharrangements. As another example, one or more antennas may be dedicatedto each frequency band for transmission and/or reception. These examplesare not limiting, however, as any suitable technique may be used toaccommodate the usage of multiple frequency bands by the UE 102 in theseand other scenarios.

FIG. 7 illustrates another example of a method of communication inaccordance with some embodiments. As mentioned previously regarding themethod 600, embodiments of the method 700 may include additional or evenfewer operations or processes in comparison to what is illustrated inFIG. 7 and embodiments of the method 700 are not necessarily limited tothe chronological order that is shown in FIG. 7. In describing themethod 700, reference may be made to FIGS. 1-6 and 8-11, although it isunderstood that the method 700 may be practiced with any other suitablesystems, interfaces and components. In addition, embodiments of themethod 700 may also be applicable to UEs 102, eNBs 104, small-cell APs106, APs, STAs or other wireless or mobile devices. The method 700 mayalso refer to an apparatus for a small-cell AP 106, eNB 104 and/or UE102 or other device described above.

It should be noted that the method 700 may be practiced at an eNB 104and may include exchanging of signals or messages with a UE 102.Similarly, the method 600 may be practiced at a UE 102 and may includeexchanging of signals or messages with an eNB 104. In some cases,operations and techniques described as part of the method 600 may berelevant to the method 700. In addition, embodiments may includeoperations performed at the eNB 104 that may be reciprocal or similar toother operations described herein performed at the UE 102. For instance,an operation of the method 700 may include transmission of a message bythe eNB 104 while an operation of the method 600 may include receptionof the same message or similar message by the UE 102.

In addition, previous discussion of various techniques and concepts maybe applicable to the method 700 in some cases, including macro-cellarrangements and devices, small-cell arrangements and devices, pencilcell arrangements and devices, APRSs, BRSs, control messages,beam-forming and others.

At operation 705, the eNB 104 may transmit, to a UE 102, a small-cellmeasurement request that indicates one or more small-cell APs 106 forwhich the UE 102 is to determine small-cell signal quality measurements.At operation 710, the eNB 104 may receive the small-cell signal qualitymeasurements from the UE 102. Although embodiments are not limited assuch, in some cases, previously described techniques for indicating thesmall-cell APs 106 may be used and previously described signal qualitymeasurements may be used.

At operation 715, the eNB 104 may determine a group of candidate pencilcells for which the UE 102 is to determine pencil cell signal qualitymeasurements. At operation 720, the eNB 104 may transmit, to the UE 102,a pencil cell measurement request that indicates the group of candidatepencil cells. The candidate pencil cells may be determined from pencilcells supported by the small-cell APs 106. In some embodiments, the eNB104 may determine that the candidate pencil cells in the group may bepossible candidates for usage by the UE 102 for pencil cell reception ofdata. As an example, the determination may be based at least partly onthe received small-cell signal quality measurements. For instance,pencil cells of small-cell APs 106 with relatively strong small-cellsignal quality measurements may be determined as candidates. As anotherexample, the determination may be based on a geographic layout of thepencil cells and directional beam patterns of the pencil cells. Forinstance, such geographic information may be used, along with thesmall-cell signal quality measurements, in the determination of thecandidate pencil cells.

At operation 725, the eNB 104 may receive pencil cell signal qualitymeasurements from the UE 102. In some embodiments, the received pencilcell signal quality measurements may be for the candidate pencil cellsindicated in the pencil cell measurement request. As a non-limitingexample, previously described signal quality measurements may be used.The measurements may be received in one or more control messages orother messages from the UE 102, which may or may not be dedicated forcommunication of the signal quality measurements.

At operation 730, the eNB 104 may select a candidate pencil cell fromthe group of candidate pencil cells for usage by the UE 102. Atoperation 735, the eNB 104 may transmit an indicator of the selectedcandidate pencil cell to the UE 102. It should also be pointed out thatthe selected candidate pencil cell and/or related information may alsobe communicated to one or more of the small-cell APs 106 (such as theparticular one that supports the selected candidate pencil cell) usingtechniques such as those previously described. For instance, the MME 122and/or the eNB 104 may communicate such information through a back-hauland/or other interface.

As an example, the selection may be based at least partly on the pencilcell signal quality measurements. As another example, the selection mayalso be based at least partly on geographic information, such as thegeographic layout information previously described. As another example,the selection may be further based at least partly on the small-cellsignal quality measurements received at operation 710. Accordingly, anycombination of such information may be used by the eNB 104 to select thepencil cell to be used by the UE 102 for reception of data. Theseexamples are not limiting, however, as other information may be used inthe selection, in addition to or instead of the information described inthese examples.

As a non-limiting example, the measurement requests may be transmittedin macro-cell channel resources at a first centimeter wave (cmW)frequency. The small-cell signal quality measurements may be based onsignals transmitted by the small-cell APs 106 in small-cell channelresources at a second cmW frequency. The pencil cell signal qualitymeasurements may be based on directional signals transmitted by thesmall-cell APs 106 in pencil cell channel resources at a millimeter wave(mmW) frequency.

FIG. 8 illustrates an example of communication between a UE and amacro-cell eNB in accordance with some embodiments. It should be notedthat embodiments are not limited by the example communication 800 shownin FIG. 8, in terms of the number, arrangement or type of components ormessages. As an example, some embodiments may or may not include allmessages and/or operations shown in the example communication 800 inFIG. 8. Some methods described herein may include some or all of theseoperations and/or similar operations, but embodiments are not limited assuch. In addition, other mobile device components and/or base stationcomponents may be used in some cases. In some cases, previous discussionof various techniques and concepts may be applicable to the examplecommunication 800, including macro-cell arrangements and devices,small-cell arrangements and devices, pencil cell arrangements anddevices, APRSs, BRSs, control messages, beam-forming and others.

At operation 805, the eNB 104 may configure a list of APRSs to bemeasured and reported by the UE 102 and may communicate the list to theUE 102. The UE 102 may detect and measure the APRSs included in the listat operation 810, and may periodically report RSRP/RSRQ and/or othermeasurements for the APRSs to the eNB 104 at operation 815. At operation820, the eNB 104 may select a number of pencil cells that may beassociated with the strongly received APRSs for measurement by the UE102. At operation 825, the eNB 104 may configure a list of BRSs to bemeasured and reported. The BRSs may be those BRSs assigned to the pencilcells determined at operation 820 in some cases. At operation 830, theUE 102 may detect and measure the indicated BRSs, and may periodicallyreport RSRP/RSRQ and/or other measurements for the BRSs to the eNB 104at operation 835. At operation 840, the eNB may select a number ofstrongly received pencil cells using any suitable technique, examples ofwhich will be described below. At operation 845, the eNB 104 mayconfigure the selected pencil cells as secondary component cells and maycommunicate such information to the UE 102. At operation 850, the UE 102may monitor the configured pencil cells for data packets.

At operations 855-870, the eNB 104 and the UE 102 may perform similaroperations to possibly select a new set of secondary pencil cells. Forinstance, in order to accommodate mobility of the UE 102, it may bebeneficial or necessary that new pencil cells with different locationsand/or directions be used in some cases.

FIG. 9 illustrates another example of a method of communication inaccordance with some embodiments. As mentioned previously regarding themethods 600 and 700, embodiments of the method 900 may includeadditional or even fewer operations or processes in comparison to whatis illustrated in FIG. 9 and embodiments of the method 900 are notnecessarily limited to the chronological order that is shown in FIG. 9.In describing the method 900, reference may be made to FIGS. 1-8 and10-11, although it is understood that the method 900 may be practicedwith any other suitable systems, interfaces and components. In addition,embodiments of the method 900 may also be applicable to UEs 102, eNBs104, small-cell APs 106, APs, STAs or other wireless or mobile devices.The method 900 may also refer to an apparatus for a small-cell AP 106,eNB 104 and/or UE 102 or other device described above.

It should be noted that the method 900 may be practiced at a small-cellAP 106 and may include exchanging of signals or messages with a UE 102.Similarly, the method 600 may be practiced at a UE 102 and may includeexchanging of signals or messages with a small-cell AP 106. In somecases, operations and techniques described as part of the method 600 maybe relevant to the method 900. In addition, embodiments may includeoperations performed at the small-cell AP 106 that may be reciprocal orsimilar to other operations described herein performed at the UE 102.For instance, an operation of the method 900 may include transmission ofa reference signal by the small-cell AP 106 while an operation of themethod 600 may include reception of the same reference signal or similarreference signal by the UE 102.

In addition, previous discussion of various techniques and concepts maybe applicable to the method 900 in some cases, including macro-cellarrangements and devices, small-cell arrangements and devices, pencilcell arrangements and devices, APRSs, BRSs, control messages,beam-forming and others.

At operation 905, the small-cell AP 106 may transmit an APRS in APRSchannel resources. Although not limited as such, the APRS may betransmitted at a centimeter wave (cmW) frequency. At operation 910, thesmall-cell AP 106 may transmit multiple BRSs in BRS channel resources.Although not limited as such, the BRS may be transmitted at a millimeterwave (mmW) frequency. In some embodiments, the BRSs may be assigned tomultiple directional pencil cells supported by the small-cell AP 106.Although embodiments are not limited as such, previously describedspecifications for the APRS and BRS (such as beam-widths) may beapplicable in some cases.

At operation 915, the small-cell AP 106 may receive an indication thatone of the pencil cells is selected for usage by the small-cell AP 106for transmission of data messages to a UE 102. As an example, the MME122, macro eNB 104 or other component may transmit such an indication tothe small-cell AP 106 as previously described, although embodiments arenot limited as such. At operation 920, the small-cell AP 106 maytransmit one or more data messages to the UE 102. In some embodiments,the transmission may be performed according to a transmission directionassigned to the selected pencil cell, as previously described. As anexample, the BRS channel resources used for the transmission of the BRSsmay also be used for transmission of the data. This example is notlimiting, however, as other channel resources may be used. The otherchannel resources may or may not overlap the BRS channel resources insome cases, and may or may not be performed at another mmW frequency insome cases.

In some embodiments, the data messages may include or may be based onthe BRS for the selected pencil cell. For instance, a data message mayinclude a data portion and may also include a control portion (such as apilot portion or other) that may be based on the BRS.

FIG. 10 illustrates example reference signals in accordance with someembodiments. The small-cell AP 1000 (which may be suitable for use asthe small-cell AP 106 in some cases) may provide APRS coverage 1010 orsmall-cell coverage as indicated by the circular region 1015. As anon-limiting example, omni-directional transmission or transmission witha beam-width that is relatively wide (like 90 degrees or higher) may beused for the APRS coverage. The small-cell AP 1000 may also provide BRScoverage 1020 or pencil cell coverage as indicated by the oval shapedregions 1025. As a non-limiting example, narrow beam-widths may be used.For instance, a range of 5-15 degrees may be used for the pencil cells.As another non-limiting example, a coverage of the APRS transmitted bythe small-cell AP 106 may be similar to an aggregated coverage of thepencil cells transmitted by the small-cell AP 106.

As an example of APRS transmission, the LTE cell-specific referencesymbol (CRS) of port 0 may be used. As another example, an LTE discoverysignal may be use. Accordingly, one or more synchronization signalsand/or the CRS of port 0 may be used. As another example, a physicalside-link discovery signal may be used. Accordingly, the small-cell AP106 may be configured to operate as a device which can be discovered bythe UE 102, such as when the UE 102 is in close proximity to thesmall-cell AP 106. It should be noted that embodiments are not limitedby these examples, as other suitable techniques may be used for APRStransmission and/or APRS design. The CSI-RS may be included in 3GPPstandards or other standards, although embodiments are not limited assuch.

As an example of BRS transmission, a periodicity and/or time-frequencyresources for the BRSs may be configured by the macro eNB 104. Asanother example, the BRS may reuse similar techniques used for LTEdiscovery signal. For instance, the BRS may include one or morebeam-specific synchronization signals and/or channel state informationreference symbols (CSI-RS). The CSI-RS may be included in 3GPP standardsor other standards, although embodiments are not limited as such. Asanother example, different BRSs used for pencil cells of the samesmall-cell AP 106 may be transmitted with different periodicities. Forinstance, BRSs of pencil cells supporting more UEs 102 and/or moretraffic may be transmitted more frequently than BRSs of pencil cellsthat support fewer UEs 102 and/or less traffic. As another example, someor all BRSs used by pencil cells of the same small-cell AP 106 may betransmitted simultaneously. For instance, the BRSs in such cases may betransmitted in a same OFDM symbol period and/or time transmissioninterval (TTI) or other time period. In such cases, the small-cell AP106 may comprise multiple RF chains and/or multiple analog beam-formersto support the simultaneous transmission of multiple beams. As anotherexample, multiple BRSs may be transmitted by a same RF chain atdifferent times. It should be noted that embodiments are not limited bythese examples, as other suitable techniques may be used for BRStransmission and/or BRS design.

FIG. 11 illustrates an example of transmission of reference signalsaccording to various periodicity parameters in accordance with someembodiments. In the first example 1110, BRSs for 8 pencil cells (labeledas BRSs 0-7) are transmitted according to a period of T. For instance,within the group of time intervals 1115, each of BRS0-BRS7 aretransmitted. Additional groups similar to 1115 may be transmitted spacedapart by an interval of T, as indicated by 1117.

In the second example 1120, BRSs for 8 pencil cells (labeled as BRSs8-15) are transmitted according to a period of 2T. For instance, withinthe group of time intervals 1125, each of BRS8-BRS15 are transmitted.Additional groups similar to 1125 may be transmitted spaced apart by aninterval of 2T, as indicated by 1127. In the third example 1130, BRSsfor 8 pencil cells (BRSs 16-23) are transmitted according to a period of4T. For instance, within the group of time intervals 1135, each ofBRS16-BRS23 are transmitted. Additional groups similar to 1135 may betransmitted spaced apart by an interval of 4T, as indicated by 1137.

As a non-limiting example, the small-cell AP 106 may be configured toperform multiple BRS transmissions in time periods that may at leastpartly overlap. For instance, the small-cell AP 106 may comprise and/ormay be configured to support three analog beam-formers, each of whichmay be used for a different pencil cell supported by the small-cell AP106. The first beam-former may be used by the small-cell AP 106 fortransmission of the BRS0-BRS7 according to the example 1110. Inaddition, the second beam-former may be used for transmission of theBRS8-BRS15 according to the example 1120 and the third beam-former maybe used for transmission of the BRS16-BRS23 according to the example1130. Accordingly, in this example of transmission of three BRSs inoverlapping time periods, the small-cell AP 106 may transmit up to threedifferent BRS simultaneously and may transmit BRSs according todifferent periodicity parameters. It should be noted that embodimentsare not limited by this example, as any suitable number of RF chainsand/or analog beam-formers may be used, and any suitable arrangement ofBRS transmission times may also be used. For instance, periodicityparameters used for each of the RF chains and/or analog beam-formers mayor may not be different in some arrangements. As described previously,the periodicity used for each pencil cell may be varied according to anumber of UEs 102 supported by the pencil cell and/or traffic loading ofthe pencil cell.

In some embodiments, the UE 102 may perform two levels of cell detectionand measurement. As an example, the first level may be used fordetection and measurement of mmW APs 106 by searching cmW APRSs. Thesecond level may be used to measure mmW pencil cells by detection BRSs.Cell IDs of the reference signals (APRS and/or BRS) that the UE 102 isto search may be determined by the eNB 104 and may be signaled to the UE102. The selected beam cell ID list for the second level measurement maybe based on uld also be noted that embodiments are not limited to thecom

In some embodiments, the first level cell detection may enable the UE102 to discover an mmW AP 106 without the need for beam acquisition. Thesecond level cell detection and measurement may be performed, in somecases, using only the BRSs signaled by the eNB 104. Accordingly, the UE102 may not need to perform exhaustive initial pencil cell searches forall possible pencil cells from all possible mmW APs 106, in some cases.

As an example, the eNB 104 may select one or more mmW pencil cells basedat least partly on reported BRS signal quality measurements. The eNB 104may configure the selected pencil cells as secondary component cells.Accordingly, the downlink beam acquisition may be inherently realized bythe pencil cell allocation. The configured mmW pencil cells may besupported by one or more mmW APs 106, in some cases. Accordingly, CoMPmay be supported in some cases.

As an example, a number of configured secondary component cells, whichmay include small-cell APs 106 and/or pencil cells, may be larger than anumber of supported secondary cells (SCells). For instance, the numberof supported SCells may be related to a standard, although embodimentsare not limited as such. In such cases, the number of supported SCellsmay be increased (in the standard or otherwise) and/or SCells may befurther aggregated with their own secondary cells. For instance, suchcells may be “order-2 secondary cells” or similar in accordance with ahierarchical cell/carrier aggregation arrangement.

In some embodiments, pencil cells may be selected as SCells using anysuitable technique. As an example, the eNB 104 may define a thresholdTbrs and pencil cells with reported RSRP/RSRQ (or other measurement)above the threshold Tbrs may be selected as secondary cells. Referringto operation 840 (FIG. 8), this technique may be referred to in FIG. 8as “method C1.”

As another example, multiple thresholds may be defined, which may helpto avoid frequent SCell reconfiguration due to environmental variation.The thresholds for k=1, 2, . . . K may be Tbrs-1, Tbrs-2, . . . Tbrs-K,for which Tbrs-1>Tbrs-2> . . . Tbrs-K. Each threshold Tbrs-k may be usedto define a pencil cell cluster which comprises Bk adjacent pencil cellscentered about the pencil cell with reported RSRP/RSRQ measurementsgreater than Tbrs-k. It may be plausible to define B1>B2> . . . >Bk. Thevariable p_j (for j=1, . . . L) may define the L BRSs reported by the UE102 to the eNB 104, each of which has a reported RSRP/RSRQ greater thanone of the thresholds Tbrs-k. The eNB 104 may select L pencil cellclusters defined as P_i, with i=1, . . . L, as the secondary cells forthe UE 102. That is, P_i may include a number of adjacent beam cellscentered around the pencil cell p_i, and the number of pencil cells inP_i may depend on which threshold the reported RSRP/RSRQ is above. Thepencil cells other than p_i included in P_i may be referred to as “guardbeams” in some cases. Referring to operation 840 (FIG. 8), thistechnique may be referred to in FIG. 8 as “method C2.” It should benoted that some embodiments may include one or more of the operationsand/or techniques described in this example, and some embodiments mayinclude additional operations and/or techniques.

As another example, secondary component pencil cells may be reconfiguredto support mobility. When updated APRS and/or BRS signal qualitymeasurements are reported from a moving or mobile UE 102 to the eNB 104,reconfiguration and/or reselection of the secondary component cells maybe performed by the eNB 104. As previously described, guard beams may beused. In addition, in some cases, the guard beams may have a potentialto become “anchor beams” for which the reported RSRQ/RSRP (or othermeasurement) may be above defined thresholds. A current configured groupof secondary pencil cells may be defined as P_current. Based on updatedBRS signal quality measurements, a new set P_new of pencil cells may bedetermined using previously described techniques and/or othertechniques. An intersection set P_work may include an intersection ofthe sets P_current and P_new. Sets of selection metrics O_current andO_new may be determined for the sets P_current and P_new, respectively.As a non-limiting example of such, each selected pencil cell in the setmay be given a weight factor according to its reported signal qualitymeasurement. In addition, some pencil cells not reported may be given apredetermined minimum weight factor in some cases. As an example, when aratio of O_current and O_new is below a particular threshold T (whichmay or may not be predefined), the beam cell reconfiguration may beperformed. This example is not limiting, however, as other suitablecomparison operations and/or other operations may be performed on thesets O_current and O_new to determine whether or not the beam cellreconfiguration is to be performed. Referring to operation 865 (FIG. 8),this technique may be referred to in FIG. 8 as “method R1.” It should benoted that some embodiments may include one or more of the operationsand/or techniques described in this example, and some embodiments mayinclude additional operations and/or techniques.

It should be noted that a handoff and/or handover of pencil cells may beinherently implemented as a result of such reconfiguration methods, insome cases. It should be noted that one or more operations included inthe examples just described (such as the reconfiguration of secondarycomponent pencil cells and selection of pencil cells as SCells) may beincluded in some embodiments, including but not limited to the methods600, 700, and 900 and the scenario 800 shown in FIG. 8.

In Example 1, an apparatus for User Equipment (UE) may comprisetransceiver circuitry and hardware processing circuitry. The hardwareprocessing circuitry may configure the transceiver circuitry to receiveone or more access point reference signals (APRS) from one or moresmall-cell access points (AP). The hardware processing circuitry mayfurther configure the transceiver circuitry to transmit, to a macro-cellEvolved Node-B (eNB), one or more AP signal quality measurements basedon the reception of the APRSs. The hardware processing circuitry mayfurther configure the transceiver circuitry to receive, from themacro-cell eNB, a pencil cell control message that indicates one or morecandidate pencil cells for which the UE is to determine signal qualitymeasurements, the candidate pencil cells supported by the small-cellAPs. The hardware processing circuitry may further configure thetransceiver circuitry to receive, from the small-cell APs, beamreference signals (BRS) for the candidate pencil cells.

In Example 2, the subject matter of Example 1, the hardware processingcircuitry to further configure the transceiver circuitry to refrain fromreception of BRSs from the small-cell APs for pencil cells not includedin the pencil cell control message.

In Example 3, the subject matter of one or any combination of Examples1-2, wherein beam-widths of the APRSs may be larger than beam-widths ofthe BRSs.

In Example 4, the subject matter of one or any combination of Examples1-3, wherein the beam-widths of the APRSs may be at least 90 degrees andthe beam-widths of the BRSs may be at most 15 degrees.

In Example 5, the subject matter of one or any combination of Examples1-4, wherein for at least one of the small-cell APs, a coverage area ofthe APRS for the small-cell AP may be larger than a combined coveragearea that comprises coverage areas of BRSs for multiple pencil cellssupported by the small-cell AP.

In Example 6, the subject matter of one or any combination of Examples1-5, wherein the pencil cell control message may be received inmacro-cell channel resources at a first centimeter wave (cmW) frequency.The APRSs may be received in small-cell channel resources at a secondcmW frequency. The BRSs may be received in pencil cell channel resourcesat a millimeter wave (mmW) frequency.

In Example 7, the subject matter of one or any combination of Examples1-6, wherein a coverage area of the macro-cell eNB may be larger than acombined coverage area that comprises coverage areas of the small-cellAPs.

In Example 8, the subject matter of one or any combination of Examples1-7, wherein at least some of the candidate pencil cells may besupported by different small-cell APs.

In Example 9, the subject matter of one or any combination of Examples1-8, wherein at least some of the candidate pencil cells may besupported by a same small-cell AP.

In Example 10, the subject matter of one or any combination of Examples1-9, wherein at least one of the small-cell APs may support multiplecandidate pencil cells for which assigned BRSs are different.

In Example 11, the subject matter of one or any combination of Examples1-10, the hardware processing circuitry to further configure thetransceiver circuitry to transmit, to the macro-cell eNB, pencil cellsignal quality measurements based on the reception of the BRSs. Thehardware processing circuitry may further configure the transceivercircuitry to receive, from the macro-cell eNB, a pencil cellconfiguration message that indicates one of the candidate pencil cellsthat is selected, by the macro-cell eNB, for exchanging of data messageswith the UE. The hardware processing circuitry may further configure thetransceiver circuitry to receive, according to the selected candidatepencil cell, a data message from a corresponding small-cell AP thatsupports the selected candidate pencil cell.

In Example 12, the subject matter of one or any combination of Examples1-11, the hardware processing circuitry to configure the transceivercircuitry to transmit, to the macro-cell Evolved Node-B (eNB), updatedpencil cell signal quality measurements for the candidate pencil cells.The hardware processing circuitry may further configure the transceivercircuitry to receive, from the macro-cell eNB, a pencil cellreconfiguration message that indicates a reconfiguration, by the UE,from the selected candidate pencil cell to a reconfigured candidatepencil cell for exchanging of data messages with the UE. The hardwareprocessing circuitry may further configure the transceiver circuitry toreceive, according to the reconfigured candidate pencil cell, a datamessage from a corresponding small-cell AP that supports thereconfigured candidate pencil cell.

In Example 13, the subject matter of one or any combination of Examples1-12, the hardware processing circuitry to further configure thetransceiver circuitry to receive, from the macro-cell eNB, a small-cellAP control message that indicates the small-cell APs from which the UEis to receive the APRSs.

In Example 14, the subject matter of one or any combination of Examples1-13, wherein the pencil cell control message may further indicate BRSsthat are assigned to the candidate pencil cells.

In Example 15, the subject matter of one or any combination of Examples1-14, wherein the UE may be arranged to operate according to a ThirdGeneration Partnership Project (3GPP) Long Term Evolution (LTE) protocolto exchange messages with the macro-eNB.

In Example 16, the subject matter of one or any combination of Examples1-15, wherein the apparatus may further include one or more antennascoupled to the transceiver circuitry for the reception of the pencilcontrol message and for the transmission of the AP signal qualitymeasurements.

In Example 17, a non-transitory computer-readable storage medium maystore instructions for execution by one or more processors to performoperations for communication by a User Equipment (UE). The operationsmay configure the one or more processors to receive, from a macro-cellEvolved Node-B (eNB), a request to determine small-cell signal qualitymeasurements based on a reception, at the UE, of access point referencesignals (APRS) from one or more small-cell access points (AP). Theoperations may further configure the one or more processors to transmit,to the macro-cell eNB, small-cell signal quality measurements that aredetermined by the UE. The operations may further configure the one ormore processors to receive, from the macro-cell eNB, a request todetermine pencil cell signal quality measurements for a group ofcandidate pencil cells supported by at least a portion of the small-cellAPs. The pencil cell signal quality measurements may be based on areception, at the UE, of directional beam reference signals (BRS) fromthe small-cell APs according to the candidate pencil cells.

In Example 18, the subject matter of Example 17, the operations tofurther configure the one or more processors to receive BRSs from thesmall-cell APs according to pencil cells included in the group ofcandidate pencil cells. The operations may further configure the one ormore processors to refrain from reception of BRSs from the small-cellAPs according to pencil cells not included in the group of candidatepencil cells.

In Example 19, the subject matter of one or any combination of Examples17-18, the operations to further configure the one or more processors totransmit, to the macro-cell eNB, pencil cell signal quality measurementsthat are determined by the UE. The operations may further configure theone or more processors to receive, from the macro-cell eNB, an indicatorof a candidate pencil cell selected by the eNB for exchanging of datamessages with the UE. The operations may further configure the one ormore processors to receive a data message, according to the selectedcandidate pencil cell, from a corresponding small-cell AP that supportsthe selected candidate pencil cell.

In Example 20, the subject matter of one or any combination of Examples17-19, wherein a first centimeter wave (cmW) frequency may be used forthe reception of the requests from the macro-cell eNB. A second cmWfrequency may be used for the reception of the APRSs. A millimeter wave(mmW) frequency may be used for the reception of the BRSs.

In Example 21, an apparatus for an Evolved Node-B (eNB) may comprisetransceiver circuitry and hardware processing circuitry. The hardwareprocessing circuitry may configure the transceiver circuitry totransmit, to a User Equipment (UE), a small-cell measurement requestthat indicates one or more small-cell access points (AP) for which theUE is to determine small-cell signal quality measurements. The hardwareprocessing circuitry may further configure the transceiver circuitry toreceive the small-cell signal quality measurements from the UE. Thehardware processing circuitry may further configure the transceivercircuitry to transmit, to the UE, a pencil cell measurement request thatindicates a group of candidate pencil cells for which the UE is todetermine pencil cell signal quality measurements. At least a portion ofthe small-cell APs may be arranged to support multiple pencil cells fordirectional transmission of data messages to the UE.

In Example 22, the subject matter of Example 21, wherein the hardwareprocessing circuitry may be configured to determine the group ofcandidate pencil cells from pencil cells supported by the small-cellAPs. The determination may be based at least partly on the receivedsmall-cell signal quality measurements.

In Example 23, the subject matter of one or any combination of Examples21-22, wherein the determination of the group of candidate pencil cellsmay be further based at least partly on a geographic layout of thepencil cells and directional beam patterns of the pencil cells.

In Example 24, the subject matter of one or any combination of Examples21-23, the hardware processing circuitry to further configure thetransceiver circuitry to receive the pencil cell signal qualitymeasurements from the UE. The hardware processing circuitry may beconfigured to select a candidate pencil cell for exchanging of datamessages with the UE. The selection may be based at least partly on thereceived pencil cell signal quality measurements. The hardwareprocessing circuitry may further configure the transceiver circuitry totransmit, to the UE, an indicator of the selected candidate pencil cell.

In Example 25, the subject matter of one or any combination of Examples21-24, wherein the measurement requests may be transmitted in macro-cellchannel resources at a first centimeter wave (cmW) frequency. Thesmall-cell signal quality measurements may be based on signalstransmitted by the small-cell APs in small-cell channel resources at asecond cmW frequency. The pencil cell signal quality measurements may bebased on directional signals transmitted by the small-cell APs in pencilcell channel resources at a millimeter wave (mmW) frequency.

In Example 26, the subject matter of one or any combination of Examples21-25, wherein the eNB may be configured to operate as a macro-cell eNBfor which a coverage area may be larger than a combined coverage areathat comprises coverage areas of the small-cell APs.

In Example 27, the subject matter of one or any combination of Examples21-26, wherein the apparatus may further include one or more antennascoupled to the transceiver circuitry for the transmission of themeasurement requests and for the reception of the small-cell signalquality measurements.

In Example 28, an apparatus for a small-cell access point (AP) maycomprise transceiver circuitry and hardware processing circuitry. Thehardware processing circuitry may configure the transceiver circuitry totransmit an access point reference signal (APRS) in APRS channelresources at a centimeter wave (cmW) frequency. The hardware processingcircuitry may further configure the transceiver circuitry to transmitmultiple beam reference signals (BRS) in BRS channel resources at amillimeter wave (mmW) frequency, wherein the BRSs are assigned tomultiple directional pencil cells supported by the small-cell AP. Thehardware processing circuitry may further configure the transceivercircuitry to receive an indication that one of the pencil cells isselected for usage by the small-cell AP for transmission of datamessages to a User Equipment (UE). The hardware processing circuitry mayfurther configure the transceiver circuitry to transmit a data messageto the UE in the BRS channel resources according to a transmissiondirection assigned to the selected pencil cell.

In Example 29, the subject matter of Example 28, wherein the datamessage may include a data portion and may further include a controlportion that is based on a corresponding BRS that is assigned to theselected pencil cell.

In Example 30, the subject matter of one or any combination of Examples28-29, wherein a beam-width of the APRS may be larger than beam-widthsof the BRSs.

In Example 31, the subject matter of one or any combination of Examples28-30, wherein the beam-width of the APRS may be at least 90 degrees andthe beam-widths of the BRSs may be at most 15 degrees.

In Example 32, the subject matter of one or any combination of Examples28-31, wherein a coverage area of the APRS may be larger than a combinedcoverage area that comprises coverage areas of the BRSs.

In Example 33, the subject matter of one or any combination of Examples28-32, wherein the apparatus may further include one or more antennascoupled to the transceiver circuitry for the transmission of the APRS,the BRSs, and the data message.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. An apparatus for User Equipment (UE), theapparatus comprising transceiver circuitry and hardware processingcircuitry, the hardware processing circuitry to configure thetransceiver circuitry to: receive one or more access point referencesignals (APRS) from one or more small-cell access points (AP); transmit,to a macro-cell base station, one or more AP signal quality measurementsbased on the reception of the APRSs; receive, from the macro-cell basestation, a pencil cell control message that indicates one or morecandidate pencil cells for which the UE is to determine signal qualitymeasurements, the candidate pencil cells supported by the small-cellAPs; and receive, from the small-cell APs, beam reference signals (BRS)for the one or more candidate pencil cells indicated in the pencil cellcontrol message; and wherein the processing circuitry is to refrain fromprocessing BRSs from the small-cell APs for pencil cells not indicatedin the pencil cell control message.
 2. The apparatus according to claim1, wherein beam-widths of the APRSs are larger than beam-widths of theBRSs.
 3. The apparatus according to claim 2, wherein the beam-widths ofthe APRSs are at least 90 degrees and the beam-widths of the BRSs are atmost 15 degrees.
 4. The apparatus according to claim 1, wherein for atleast one of the small-cell APs, a coverage area of the APRS for thesmall-cell AP is larger than a combined coverage area that comprisescoverage areas of BRSs for multiple pencil cells supported by thesmall-cell AP.
 5. The apparatus according to claim 1, wherein: thepencil cell control message is received in macro-cell channel resourcesat a first centimeter wave (cmW) frequency, the APRSs are received insmall-cell channel resources at a second cmW frequency, and the BRSs arereceived in pencil cell channel resources at a millimeter wave (mmW)frequency.
 6. The apparatus according to claim 1, wherein a coveragearea of the macro-cell base station is larger than a combined coveragearea that comprises coverage areas of the small-cell APs.
 7. Theapparatus according to claim 1, wherein at least some of the candidatepencil cells are supported by different small-cell APs.
 8. The apparatusaccording to claim 1, wherein at least some of the candidate pencilcells are supported by a same small-cell AP.
 9. The apparatus accordingto claim 1, wherein at least one of the small-cell APs supports multiplecandidate pencil cells for which assigned BRSs are different.
 10. Theapparatus according to claim 1, the hardware processing circuitry tofurther configure the transceiver circuitry to: transmit, to themacro-cell base station, pencil cell signal quality measurements basedon the reception of the BRSs; receive, from the macro-cell base station,a pencil cell configuration message that indicates one of the candidatepencil cells that is selected, by the macro-cell base station, forexchanging of data messages with the UE; and receive, according to theselected candidate pencil cell, a data message from a correspondingsmall-cell AP that supports the selected candidate pencil cell.
 11. Theapparatus according to claim 10, the hardware processing circuitry tofurther configure the transceiver circuitry to: transmit, to themacro-cell base station, updated pencil cell signal quality measurementsfor the candidate pencil cells; receive, from the macro-cell basestation, a pencil cell reconfiguration message that indicates areconfiguration, by the UE, from the selected candidate pencil cell to areconfigured candidate pencil cell for exchanging of data messages withthe UE; and receive, according to the reconfigured candidate pencilcell, a data message from a corresponding small-cell AP that supportsthe reconfigured candidate pencil cell.
 12. The apparatus according toclaim 1, the hardware processing circuitry to further configure thetransceiver circuitry to receive, from the macro-cell base station, asmall-cell AP control message that indicates the small-cell APs fromwhich the UE is to receive the APRSs.
 13. The apparatus according toclaim 1, wherein the pencil cell control message further indicates BRSsthat are assigned to the candidate pencil cells.
 14. The apparatusaccording to claim 1, wherein the UE is arranged to operate according toa Third Generation Partnership Project (3GPP) protocol to exchangemessages with the macro-cell base station.
 15. The apparatus accordingto claim 1, wherein the apparatus further includes one or more antennascoupled to the transceiver circuitry for the reception of the pencilcontrol message and for the transmission of the AP signal qualitymeasurements.
 16. A non-transitory computer-readable storage medium thatstores instructions for execution by one or more processors to performoperations for communication by a User Equipment (UE), the operations toconfigure the one or more processors to: receive, from a macro-cell basestation, a request to determine small-cell signal quality measurementsbased on a reception, at the UE, of access point reference signals(APRS) from one or more small-cell access points (AP); transmit, to themacro-cell base station, small-cell signal quality measurements that aredetermined by the UE; and receive, from the macro-cell base station, arequest to determine pencil cell signal quality measurements for a groupof candidate pencil cells supported by at least a portion of thesmall-cell APs, wherein the pencil cell signal quality measurements arebased on a reception, at the UE, of directional beam reference signals(BRS) from the small-cell APs according to the candidate pencil cells;receive BRSs from the small-cell APs according to pencil cells includedin the group of candidate pencil cells, and refrain from processing BRSsfrom the small-cell APs according to pencil cells not included in thegroup of candidate pencil cells.
 17. The non-transitorycomputer-readable storage medium according to claim 16, the operationsto further configure the one or more processors to: transmit, to themacro-cell base station, pencil cell signal quality measurements thatare determined by the UE; receive, from the macro-cell base station, anindicator of a candidate pencil cell selected by the base station forexchanging of data messages with the UE; and receive a data message,according to the selected candidate pencil cell, from a correspondingsmall-cell AP that supports the selected candidate pencil cell.
 18. Thenon-transitory computer-readable storage medium according to claim 16,wherein: a first centimeter wave (cmW) frequency is used for thereception of the requests from the macro-cell base station, a second cmWfrequency is used for the reception of the APRSs, and a millimeter wave(mmW) frequency is used for the reception of the BRSs.
 19. An apparatusfor a base station, the apparatus comprising transceiver circuitry andhardware processing circuitry, the hardware processing circuitry toconfigure the transceiver circuitry to: transmit, to a User Equipment(UE), a small-cell measurement request that indicates one or moresmall-cell access points (AP) for which the UE is to determinesmall-cell signal quality measurements; receive the small-cell signalquality measurements from the UE; and transmit, to the UE, a pencil cellmeasurement request that indicates a group of candidate pencil cells forwhich the UE is to determine pencil cell signal quality measurements,wherein at least a portion of the small-cell APs are arranged to supportmultiple pencil cells for directional transmission of data messages tothe UE, wherein the measurement requests are transmitted in macro-cellchannel resources at a first centimeter wave (cmW) frequency, whereinthe small-cell signal quality measurements are based on signalstransmitted by the small-cell APs in small-cell channel resources at asecond cmW frequency, and wherein the pencil cell signal qualitymeasurements are based on directional signals transmitted by thesmall-cell APs in pencil cell channel resources at a millimeter wave(mmW) frequency.
 20. The apparatus according to claim 19, wherein thehardware processing circuitry is configured to determine the group ofcandidate pencil cells from pencil cells supported by the small-cellAPs, the determination based at least partly on the received small-cellsignal quality measurements.
 21. The apparatus according to claim 19,wherein the determination of the group of candidate pencil cells isfurther based at least partly on a geographic layout of the pencil cellsand directional beam patterns of the pencil cells.
 22. The apparatusaccording to claim 19, the hardware processing circuitry furtherconfigured to: configure the transceiver circuitry to receive the pencilcell signal quality measurements from the UE; select a candidate pencilcell for exchanging of data messages with the UE, the selection based atleast partly on the received pencil cell signal quality measurements;and configure the transceiver circuitry to transmit, to the UE, anindicator of the selected candidate pencil cell.
 23. The apparatusaccording to claim 19, wherein: the measurement requests are transmittedin macro-cell channel resources at a first centimeter wave (cmW)frequency, the small-cell signal quality measurements are based onsignals transmitted by the small-cell APs in small-cell channelresources at a second cmW frequency, and the pencil cell signal qualitymeasurements are based on directional signals transmitted by thesmall-cell APs in pencil cell channel resources at a millimeter wave(mmW) frequency.
 24. The apparatus according to claim 19, wherein thebase station is configured to operate as a macro-cell base station forwhich a coverage area is larger than a combined coverage area thatcomprises coverage areas of the small-cell APs.
 25. The apparatusaccording to claim 19, wherein the apparatus further includes one ormore antennas coupled to the transceiver circuitry for the transmissionof the measurement requests and for the reception of the small-cellsignal quality measurements.
 26. An apparatus for a small-cell accesspoint (AP), the apparatus comprising transceiver circuitry and hardwareprocessing circuitry, the hardware processing circuitry to configure thetransceiver circuitry to: transmit an access point reference signal(APRS) in APRS channel resources at a centimeter wave (cmW) frequency;transmit multiple beam reference signals (BRS) in BRS channel resourcesat a millimeter wave (mmW) frequency, wherein the BRSs are assigned tomultiple directional pencil cells supported by the small-cell AP;receive an indication that one of the pencil cells is selected for usageby the small-cell AP for transmission of data messages to a UserEquipment (UE); and transmit a data message to the UE in the BRS channelresources according to a transmission direction assigned to the selectedpencil cell, wherein a coverage area of the APRS is larger than acombined coverage area that comprises coverage areas of the BRSs. 27.The apparatus according to claim 26, wherein the data message includes adata portion and further includes a control portion that is based on acorresponding BRS that is assigned to the selected pencil cell.
 28. Theapparatus according to claim 26, wherein a beam-width of the APRS islarger than beam-widths of the BRSs.
 29. The apparatus according toclaim 28, wherein the beam-width of the APRS is at least 90 degrees andthe beam-widths of the BRSs are at most 15 degrees.
 30. The apparatusaccording to claim 26, wherein the apparatus further includes one ormore antennas coupled to the transceiver circuitry for the transmissionof the APRS, the BRSs, and the data message.